“No, don’t!” the man cried. “It might not be safe out there. What if you trigger another rockslide?”

“I’m not going to touch anything. I’m just going to take a quick look and see how far we are from the station. I’ll be careful.” The doors finally slid apart far enough to let me squeeze through, and I stepped out onto a rocky cave floor.

Wait. The tunnel’s floor, ceiling, and walls had been lined with concrete. But there was no sign of concrete here, not even scattered crumbs of it. Beneath my feet lay rough, unhewn stone, scattered and piled with rocks that ranged from pea-gravel to boulders. I sniffed: wet rocks and stagnant water and a hint of bat guano, scents remembered from a long-ago trip to Carlsbad. Though I also caught a faint scent of…fireworks? Weird.

I turned first toward the glowing green curtain, but it was clear that, at least on this side of the train, it covered the entire tunnel opening from which the front half of the train car had emerged. Cautiously, I stepped forward to examine the edges of the curtain more closely. Maybe there was a way to squeeze past, if we were very determined. I squinted; through the curtain, I could make out smooth concrete walls, a low ceiling, and the side of the train car through the green glimmer, but not even the smallest gap between concrete and curtain. “Damn. Well, okay, then. Concourse B it is.”

As I turned to see just how close we were to the Concourse B train station, though, it finally penetrated my aching skull that the space I was in was far too large to be a collapsed train tunnel. The wavering green light from the shimmering curtain did not reach as far as the walls and ceiling of the vast cavern. I could only guess how far away they were, but now that I’d taken a few steps away from the train, I could feel a gentle breeze against my face. I was obviously nowhere near Concourse B. A cold chill rattled my spine. “I don’t think we’re in Kansas anymore, Toto,” I murmured.

I rubbed the sore spot on the back of my head. I’d hit it pretty hard; perhaps this was a hallucination? I turned back toward the train. No, it still looked like the airport train, except where a boulder had crumpled up the nose. So where was the train station that couldn’t possibly be more than a hundred yards away?

All right, I told myself. Deep breath. If we can’t get to Concourse B, we’ll just have to find a way back into the train tunnel. Did I dare circle around the end of the train to check out the other side and see if perhaps there was a gap in the curtain there? I remembered what the guy in the train had said about triggering another rockslide, but the ceiling was so far above me that I couldn’t imagine anything I could do that would affect it. Still, something about the huge cavern made me edgy; I could feel the hairs on the back of my neck standing on end. I decided to exercise the better part of valor and return to the train car to wait for help to arrive.

As I stepped toward the train, though, a bar slid horizontally across my chest from left to right, blocking my path. It looked like wood, or maybe horn; it was about six feet long, slightly curved, with a ridge down the length of it. “Hey, what?” I reached for the end of it, to push it out of my way, but jerked back almost instantly. “Ouch!” The tip and about the first foot of the thing were razor-sharp. I gazed at my bloody hand in shock.